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DS: Fachverband Dünne Schichten
DS 26: [CPP] Organic Electronics and Photovoltaics III (Joint Session DS/CPP/HL/O)
DS 26.6: Talk
Wednesday, March 24, 2010, 11:00–11:15, H37
Structural and morphological changes in P3HT thin film transistors applying an electric field — •Deepak kumar Tiwari1, Souren Grigorian1, Ullrich Pietsch1, Heinz Flesch1,2, and Roland Resel1,2 — 1University of siegen, siegen, Germany — 2Graz University of technology
We report on electric field dependent crystalline structure and morphological changes of drop casting and spin coated poly(3-hexyltheiopine) (P3HT) thin films. In order to probe the morphological changes induced by an applied electric field the samples were covered with thin source/drain electrodes separated by a small channel of 2 mm width. A series of x-ray reflectivity, X-ray grazing incidence out-of-plane and in-plane scans have been performed as function of the applied electric voltage. The (100) peak shows a decrease in intensity with increase of the applied electric field. This might be caused by Joule heating and the creation of current induced defects in the P3HT film. On other hand the (020) peak intensity shows much stronger changes with applied field. Considering the *-* stacking direction the measured effect can be directly related to a change in the electric transport. The observed changes in structure are reversible and the current-voltage cycle can be repeated several times. For X-ray reflectivity major changes have been found close to critical angle of total external reflection indicating the film becomes less dense and increases in surface roughness with increase of the voltage. This change in surface behaviour could be confirmed by in-situ AFM measurements.